PPA: offset with 627?
Jun 7, 2004 at 9:42 PM Thread Starter Post #1 of 5

Akku

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I am trying OPA627 in my PPA but I got an higher offset than with the 8610.
With 8610 I managed, moving op-amps in the channels, to get an almost null offset (0.1-0.2mv in al three chnls). With 627 I got 2.0mv in L and R and 0.1 in G and there are no changes moving the op-amps from chnl to chnl.
Normal? According to Tangent 2 mv is not so bad, isn't it?
I have omitted C3's, adding them can help?
Thank you
 
Jun 8, 2004 at 1:04 AM Post #2 of 5

tangent

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The AD8610 has among the highest DC precision you'll find short of chips designed specifically for DC performance. The OPA627 isn't bad, but it's normal for it to not give quite as stellar a performance in this regard as the AD8610.

2mV of offset isn't worth worrying about at all. Even with a 10x bass boost, you're only at 20mV, which is quite tolerable.
 
Jun 8, 2004 at 12:04 PM Post #3 of 5

Akku

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... since I don't even have a bass boost.
Thank you Tangent
 
Jun 9, 2004 at 3:57 AM Post #4 of 5

Sovkiller

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Quote:

Originally Posted by tangent
The OPA627 isn't bad, but it's normal for it to not give quite as stellar a performance in this regard as the AD8610.


I now that some of the DIYers are true defenders of the AD8610, but IMPE, with the bassboost on, I got less than 1mV with the OPA627BP's and about 6-7 mV with the regular ADs, so this is not a general rule IMO, due to production tolerances etc...maybe is becasue of the BP category of the OPAs, but this makes about 7 times the value of DC offset for the ADs compared to the OPAs...maybe as a genral rule they behave like that, but in some cases (as this one) it was not like that, this was one of the things that makes me re-sell the ADs (sound preference appart)
 
Jun 9, 2004 at 4:55 AM Post #5 of 5

tangent

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Quote:

maybe is becasue of the BP category of the OPAs


Yes, that's exactly the reason. The reason the B version costs twice as much is that it is specially selected for excellent DC specs.
 

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